[Update]Wurkkos dual LEDs 21700 Headlamp design Photos/UI update~

This chart does not show that the light will do that before the battery is extremely low. You’d need a runtime chart of that lower mode to see if it drops proportionally over a discharge cycle. In Maukka’s test Vf for 100lm from a 90CRI LH351D is only 2.7V.

Again, the only lights that can sustain brightness like that are those with boost drivers, or multiple cells (with combined voltage exceeding emitter VF) + a buck driver. As soon as the voltage at the emitter drops below the Vf required for a given output, that output will start to decrease. This happens with lights that have an extra 7135 channel for low modes as well since they also cannot step-up voltage.

What are some of the “real lights” that don’t have a drop in output like the graph you posted? What type of alternative driver would you propose for this light?

I think the contentious point is using either linear drivers or FET + sense resistor, vs just PWMing a FET.

The former will probably have constant output (smoother with no PWM, and constant current/lumens), vs just having a fraction of max output (FET-DDed LED crowbarred across the ever-decreasing cell voltage).

It’s switching the light on medium for 600lm across most of the cell’s SOC, vs 800…750…700…650… etc. lm as the cell drains.

Did I mansplain that about right? :laughing:

Oh, good point. I was under the impression that most of the single-cell, 3V emitter Sofirn and Wurkkos lights use CC, not PWM’ed FET so that’s what I’m assuming is planned for this light.

Wellp, that constant-downward-slope line AEDE referred to was the latter, ie, the bad one.

To me, that’s like 3×AAA lights that start out nice’n’bright, then start slumping almost in seconds, and just get dimmer and dimmer and dimmer ’til you change the batteries. And you have no idea how bright nor can guesstimate the current that way, either. So runtime is always a surprise, and not necessarily a good one.

Here I was convinced the driver of the FC11 was CC, I’ll be damned. Zak’s review confirms there is PWM on every mode except turbo. :open_mouth:

But still, regardless whether a PWM’ed FET is used or a CC linear, or 7135 chips… without excess voltage, output will decline with cell charge. There is literally no getting around this, and with high Vf emitters it is even more noticeable. The big difference is in efficiency and the presence of PWM.

Graph show driver behaviour only.
No.Voltage drop on 351D is ~2.7V. 18650 under 3V have ~5% of energy. So during 95% of battery energy output can be stable using buck or linear driver. After that 95% I can simply change battery.

Any light with li-ion battery. Just look at discharge curve.

Look at the S2+ Med runtime on this graph, as soon as it drops below required Vf for that mode output declines with voltage. This will be consistent in direct drive and linear vs boost or buck driver.

A Zebralight with boost driver has this result, due to voltage step-up with boost circuit. ^ That is what many reviewers and members on here simply consider “regulation”. There is a a huge difference.

Even the buck driver in the SP31v2 drops output once cell voltage is low. A cell at “X” voltage simply can’t supply more without a boost circuit.

As you said, since the Vf is so low with lower outputs there is little benefit to buck driver in a 3V, single cell light (other than losing voltage as heat earlier in the discharge curve). I would love to see more buck drivers since there’s little disadvantage, but for a budget light I’m never upset with a CC linear driver either.

100% agreed that PWM’ed FET has too many downsides other than a boost in max output with full cells :+1: I was unaware that was what was used in the FC11, and hope this light utilizes something else as well.

Ironically, that’s where linear shines(haha).

Especially with low Vf LEDs, you get stable consistent output for most of the cell’s SOC, and then at the tail end it’ll start going dimmer and allow you plenty of time to react.

And that’s even vs a boost circuit that’ll hold consistent output ’til a few seconds before it craps out completely as the cell winds down to zero.

Behaviour of work at low charge is determined by software in boost driver. It may slowly decrease output, may to step down, may work comined way.

It wasn’t the thermal regulation that was the issue on the C8G, there is a step down that occurs after 30 sec on any brightness above 900 lumens

I apologize for derailing the conversation with a little off topic question.

What would it take to have a multi LED headlamp with a RED LED (XP-E2 deep red) just like in the WK30?

Strap the WK30 to your head :stuck_out_tongue:

Lol Funtastic idea :slight_smile:

I just verified that with H03 with a magnetic tailcap. You don’t have to use a compass, many phones have a magnetometer to find directions of travel, and will get confused by the magnet in headlamp.

Any new news about this project?

Please check me if this question is culturally insensitive, but what’s with the long pinky nail? Is it to denote class or is a home-grown cocaine spoon? Also this is huge for a headlamp. Cool concept though.

There's more to come very soon. Please stay tuned. :-)

Tagging so I get updates. I like the recharge capability and throw and flood on same unit.

What is your take on a magnetic tailcap with a removable magnet. The actual magnet can be removed or installed. Maybe something simple like this magnet ring that would fit perfectly in the tail?

Looks interesting. I have never tried this before with any of my stock lights. I suppose this ring will surround the tailcap spring, being in direct contact between the tailcap's inner wall and the negative pole of the battery, right? Maybe it could become difficult to fully screw the tailcap back on the tube if the magnet ring leaves less space for spring compression?